Preheat the oven to 180ºC (350°F).
In a Dutch oven, heat 1 tablespoon of olive oil over medium-high heat until it gets hot. Add the ground beef, season with salt and pepper, and cook, stirring occasionally and breaking it up with a wooden spoon, until browned and cooked through, about 5 minutes.
3 tablespoons olive oil, 1 pound ground beef
Transfer the beef to a plate, and drain any excess fat from the pot if necessary.
Return the pot to medium-high heat and add the remaining 2 tablespoons of olive oil, along with the onion and peppers. Cook, stirring occasionally, until the vegetables begin to soften, about 5 minutes.
1 cup yellow onion, 1 cup green bell pepper, 1 cup red bell pepper
Add the garlic and red pepper flakes, cooking until the garlic is fragrant and lightly golden, about 1 minute. Stir in the tomato paste and dried oregano, cooking frequently until the tomato paste darkens in color, 1 to 2 minutes.
5 garlic cloves, ¼ teaspoon red pepper flakes, 3 tablespoons tomato paste, ½ teaspoon dried oregano
Return the beef and any accumulated juices to the pot. Add chicken broth, a can of diced fire-roasted tomatoes with their juices, and Worcestershire sauce.
1 ½ cups low-sodium chicken broth, 1 can diced fire-roasted tomatoes, 2 teaspoons Worcestershire sauce
Stir in long-grain white rice, season with salt and pepper to taste, and bring to a boil.
1 cup long grain white rice, Salt and pepper
Transfer to a casserole dish and top with cheese. Bake for 12 minutes, or until golden and bubbly.
½ mozzarella cheese
Serve with fresh parsley.
Fresh parsley